/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.dolphinscheduler.common.utils;

import static java.util.Collections.emptyList;

import org.apache.dolphinscheduler.common.constants.Constants;

import org.apache.commons.collections.CollectionUtils;

import java.io.IOException;
import java.net.Inet6Address;
import java.net.InetAddress;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.Enumeration;
import java.util.LinkedList;
import java.util.List;
import java.util.Objects;
import java.util.Optional;
import java.util.regex.Pattern;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * NetUtils
 */
public class NetUtils {

  private static final Pattern IP_PATTERN = Pattern.compile("\\d{1,3}(\\.\\d{1,3}){3,5}$");
  private static final String NETWORK_PRIORITY_DEFAULT = "default";
  private static final String NETWORK_PRIORITY_INNER = "inner";
  private static final String NETWORK_PRIORITY_OUTER = "outer";
  private static final Logger logger = LoggerFactory.getLogger(NetUtils.class);
  private static InetAddress LOCAL_ADDRESS = null;
  private static volatile String HOST_ADDRESS;

  private NetUtils() {
    throw new UnsupportedOperationException("Construct NetUtils");
  }

  /**
   * get addr like host:port
   *
   * @return addr
   */
  public static String getAddr(String host, int port) {
    return String.format("%s:%d", host, port);
  }

  /**
   * get addr like host:port
   *
   * @return addr
   */
  public static String getAddr(int port) {
    return getAddr(getHost(), port);
  }

  /**
   * get host
   *
   * @return host
   */
  public static String getHost(InetAddress inetAddress) {
    if (inetAddress != null) {
      if (Constants.KUBERNETES_MODE) {
        String canonicalHost = inetAddress.getCanonicalHostName();
        String[] items = canonicalHost.split("\\.");
        if (items.length == 6 && "svc".equals(items[3])) {
          return String.format("%s.%s", items[0], items[1]);
        }
        return canonicalHost;
      }
      return inetAddress.getHostAddress();
    }
    return null;
  }

  public static String getHost() {
    if (HOST_ADDRESS != null) {
      return HOST_ADDRESS;
    }

    InetAddress address = getLocalAddress();
    if (address != null) {
      HOST_ADDRESS = getHost(address);
      return HOST_ADDRESS;
    }
    return Constants.KUBERNETES_MODE ? "localhost" : "127.0.0.1";
  }

  private static InetAddress getLocalAddress() {
    if (null != LOCAL_ADDRESS) {
      return LOCAL_ADDRESS;
    }
    return getLocalAddress0();
  }

  /**
   * Find first valid IP from local network card
   *
   * @return first valid local IP
   */
  private static synchronized InetAddress getLocalAddress0() {
    if (null != LOCAL_ADDRESS) {
      return LOCAL_ADDRESS;
    }

    InetAddress localAddress = null;
    try {
      NetworkInterface networkInterface = findNetworkInterface();
      if (networkInterface != null) {
        Enumeration<InetAddress> addresses = networkInterface.getInetAddresses();
        while (addresses.hasMoreElements()) {
          Optional<InetAddress> addressOp = toValidAddress(addresses.nextElement());
          if (addressOp.isPresent()) {
            try {
              if (addressOp.get().isReachable(200)) {
                LOCAL_ADDRESS = addressOp.get();
                return LOCAL_ADDRESS;
              }
            } catch (IOException e) {
              logger.warn("test address id reachable io exception", e);
            }
          }
        }
      }

      localAddress = InetAddress.getLocalHost();
    } catch (UnknownHostException e) {
      logger.warn("InetAddress get LocalHost exception", e);
    }
    Optional<InetAddress> addressOp = toValidAddress(localAddress);
    if (addressOp.isPresent()) {
      LOCAL_ADDRESS = addressOp.get();
    }
    return LOCAL_ADDRESS;
  }

  private static Optional<InetAddress> toValidAddress(InetAddress address) {
    if (address instanceof Inet6Address) {
      Inet6Address v6Address = (Inet6Address) address;
      if (isPreferIPV6Address()) {
        return Optional.ofNullable(normalizeV6Address(v6Address));
      }
    }
    if (isValidV4Address(address)) {
      return Optional.of(address);
    }
    return Optional.empty();
  }

  private static InetAddress normalizeV6Address(Inet6Address address) {
    String addr = address.getHostAddress();
    int i = addr.lastIndexOf('%');
    if (i > 0) {
      try {
        return InetAddress.getByName(addr.substring(0, i) + '%' + address.getScopeId());
      } catch (UnknownHostException e) {
        logger.debug("Unknown IPV6 address: ", e);
      }
    }
    return address;
  }

  public static boolean isValidV4Address(InetAddress address) {

    if (address == null || address.isLoopbackAddress()) {
      return false;
    }
    String name = address.getHostAddress();
    return (name != null
        && IP_PATTERN.matcher(name).matches()
        && !address.isAnyLocalAddress()
        && !address.isLoopbackAddress());
  }

  /**
   * Check if an ipv6 address
   *
   * @return true if it is reachable
   */
  private static boolean isPreferIPV6Address() {
    return Boolean.getBoolean("java.net.preferIPv6Addresses");
  }

  /**
   * Get the suitable {@link NetworkInterface}
   *
   * @return If no {@link NetworkInterface} is available , return <code>null</code>
   */
  private static NetworkInterface findNetworkInterface() {

    List<NetworkInterface> validNetworkInterfaces = emptyList();

    try {
      validNetworkInterfaces = getValidNetworkInterfaces();
    } catch (SocketException e) {
      logger.warn("ValidNetworkInterfaces exception", e);
    }

    NetworkInterface result = null;
    // Try to specify config NetWork Interface
    for (NetworkInterface networkInterface : validNetworkInterfaces) {
      if (isSpecifyNetworkInterface(networkInterface)) {
        result = networkInterface;
        break;
      }
    }

    if (null != result) {
      return result;
    }
    return findAddress(validNetworkInterfaces);
  }

  /**
   * Get the valid {@link NetworkInterface network interfaces}
   *
   * @throws SocketException SocketException if an I/O error occurs.
   */
  private static List<NetworkInterface> getValidNetworkInterfaces() throws SocketException {
    List<NetworkInterface> validNetworkInterfaces = new LinkedList<>();
    Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
    while (interfaces.hasMoreElements()) {
      NetworkInterface networkInterface = interfaces.nextElement();
      if (ignoreNetworkInterface(networkInterface)) { // ignore
        continue;
      }
      validNetworkInterfaces.add(networkInterface);
    }
    return validNetworkInterfaces;
  }

  /**
   * @param networkInterface {@link NetworkInterface}
   * @return if the specified {@link NetworkInterface} should be ignored, return <code>true</code>
   * @throws SocketException SocketException if an I/O error occurs.
   */
  public static boolean ignoreNetworkInterface(NetworkInterface networkInterface) throws SocketException {
    return networkInterface == null
        || networkInterface.isLoopback()
        || networkInterface.isVirtual()
        || !networkInterface.isUp();
  }

  private static boolean isSpecifyNetworkInterface(NetworkInterface networkInterface) {
    String preferredNetworkInterface = PropertyUtils.getString(Constants.DOLPHIN_SCHEDULER_NETWORK_INTERFACE_PREFERRED,
        System.getProperty(Constants.DOLPHIN_SCHEDULER_NETWORK_INTERFACE_PREFERRED));
    return Objects.equals(networkInterface.getDisplayName(), preferredNetworkInterface);
  }

  private static NetworkInterface findAddress(List<NetworkInterface> validNetworkInterfaces) {
    if (CollectionUtils.isEmpty(validNetworkInterfaces)) {
      return null;
    }
    String networkPriority = PropertyUtils.getString(Constants.DOLPHIN_SCHEDULER_NETWORK_PRIORITY_STRATEGY, NETWORK_PRIORITY_DEFAULT);
    if (NETWORK_PRIORITY_DEFAULT.equalsIgnoreCase(networkPriority)) {
      return findAddressByDefaultPolicy(validNetworkInterfaces);
    } else if (NETWORK_PRIORITY_INNER.equalsIgnoreCase(networkPriority)) {
      return findInnerAddress(validNetworkInterfaces);
    } else if (NETWORK_PRIORITY_OUTER.equalsIgnoreCase(networkPriority)) {
      return findOuterAddress(validNetworkInterfaces);
    } else {
      logger.error("There is no matching network card acquisition policy!");
      return null;
    }
  }

  private static NetworkInterface findAddressByDefaultPolicy(List<NetworkInterface> validNetworkInterfaces) {
    NetworkInterface networkInterface;
    networkInterface = findInnerAddress(validNetworkInterfaces);
    if (networkInterface == null) {
      networkInterface = findOuterAddress(validNetworkInterfaces);
      if (networkInterface == null) {
        networkInterface = validNetworkInterfaces.get(0);
      }
    }
    return networkInterface;
  }

  /**
   * Get the Intranet IP
   *
   * @return If no {@link NetworkInterface} is available , return <code>null</code>
   */
  private static NetworkInterface findInnerAddress(List<NetworkInterface> validNetworkInterfaces) {

    NetworkInterface networkInterface = null;
    for (NetworkInterface ni : validNetworkInterfaces) {
      Enumeration<InetAddress> address = ni.getInetAddresses();
      while (address.hasMoreElements()) {
        InetAddress ip = address.nextElement();
        if (ip.isSiteLocalAddress()
            && !ip.isLoopbackAddress()) {
          networkInterface = ni;
        }
      }
    }
    return networkInterface;
  }

  private static NetworkInterface findOuterAddress(List<NetworkInterface> validNetworkInterfaces) {
    NetworkInterface networkInterface = null;
    for (NetworkInterface ni : validNetworkInterfaces) {
      Enumeration<InetAddress> address = ni.getInetAddresses();
      while (address.hasMoreElements()) {
        InetAddress ip = address.nextElement();
        if (!ip.isSiteLocalAddress()
            && !ip.isLoopbackAddress()) {
          networkInterface = ni;
        }
      }
    }
    return networkInterface;
  }

}
